AE8018-AirTrafficControlandPlanning

Unit–1 BASICCONCEPTS
Objectives of ATS - Parts of ATC service – Scope and Provision of ATCs – VFR &
IFR operations – Classification of ATS air spaces – Varies kinds of separation –
Altimeter setting procedures – Establishment, designation and identification of units
providing ATS – Division of responsibility of control.

1. ObjectivesofATS

Theobjectivesoftheairtrafficservicesshallbeto:

1. Preventcollisionsbetweenaircraft
2. Preventcollisionsbetweenaircraftonthe maneuveringareaandobstructions on that
area
3. Expediteandmaintainanorderlyflowofairtraffic;
4. Provideadviceandinformationusefulforthesafeandefficientconductof flights
5. Notify appropriate organizations regarding aircraft in need of search and rescue
aid, and assist such organizations as required.

2. PartsofATCservice

In order to accomplish the previous objectives, the air traffic services are divided into
three parts:

1. Airtrafficcontrolservice,
2. Flightinformationserviceand
3. Alertingservice

Air traffic control service will accomplish the objectives of preventing all collisions
between aircraft and expediting and maintaining an orderly flow of air traffic

Flightinformation servicewillaccomplish theobjectivesof providingadviceand

information useful for the safe and efficient conduct of flights

1
 Alerting service willaccomplishtheobjectives ofnotifyingappropriateorganizations
regarding aircraft in need of search and rescue.

Airtrafficcontrolservice
AirtrafficcontrolserviceorATSshallbeprovided:
 toallIFRflightsinairspaceclassesA,B,C,DandE
 toallVFR flightsinairspaceclassesB,CandD
 toallspecialVFRflights
 toallaerodrometrafficatcontrolledaerodromes

Theairtrafficcontrolservice isdivided inthreesub-partsasfollows:

1. Area control service: the provision of air traffic control service for en-route
controlled flights except the aircraft associated with arrival or departure routes
or ground movements.
The area control service shall be provided by area control centre or, where no
areacontrolcentre isestablished, bythe unit providingapproachcontrolservice in a
control area of limited extent.

2. Approach control service: the provision of air traffic control service for
controlled flights associated with arrival or departure except the aircraft
associated with ground movements.
The approach control service shall be provided by an approach control unit
whenit is necessaryordesirabletoestablishaseparate unitor, byanaerodrome
control tower or area control center when it is necessary to combine under the
responsibility of one unit the functions of the approach control service.

3. Aerodrome control service: the provision of air traffic control service for
aerodrome traffic located around the airfield. The Aerodrome control service
shall be provided by an aerodrome control tower.

The possibility of extended control which is permitted by the regulation is subject

toyour national regulation authorization.

2
 And controlling outside your responsibility area is forbidden in IVAO except when
national regulation permits it, or when it is published clearly on charts.

Inordertoprovideairtrafficcontrolservice,anairtrafficcontrolunitshall:
 Be provided with information on the intended movement of each aircraft, or
variations thereof, and with current information on the actual progress of each
aircraft;
 determine from the information received, the relative positions of known
aircraft to each other;
 Issue clearances and information for the purpose of preventing collision
betweenaircrafts under its controland ofexpeditingand maintaining anorderly
flow of traffic;
 Coordinate clearances as necessary with other units whenever an aircraft might
otherwise conflict with traffic operated under the control of such other units or
before transferring control of an aircraft to such other units

FlightinformationService
1. Flight information service will accomplish the objectives of providing advice
and information useful for the safe and efficient conduct of flights
2. Flight informationservice shallbe provided to allaircraft whichare likelyto be
affected by the information.
3. Flight information service does not relieve the pilot-in-command of an aircraft
of any responsibilities and the pilot-in-command has to make the final decision
regarding any suggested alteration of flight plan.
4. The provision of air traffic control service shall have precedence over the
provision of flight information service whenever the provisions of air traffic
control service so requires.
Flight information service provided to flights shall include the provision of
information concerning:
 weather conditions reported or forecast at departure, destination and alternate
aerodromes
 collisionhazards,toaircraftoperatinginairspaceclassesC,D,E,FandG

3
  anyavailable informationofsurface sea vessels in the area for flight over water
areas when requested by a pilot (not simulated by IVAO except in somespecific
scenery)
 SIGMETandAIRMETinformation
 Informationconcerningvolcaniceruptionsandvolcanicashclouds(notsimulated in
IVAO)
 Information concerning the release into the atmosphere of toxic chemicals (not
simulated in IVAO)
 Informationoftheserviceabilityofnavigationaids
 Informationonchangesinconditionofaerodromesandassociatedfacilities,
including information on the state of the aerodrome movement areas
 Anyotherinformationlikelytoaffectsafety
ATIS-automaticterminalinformationservice
The meteorological information and operational information concerning navigation
aids and aerodromes included in the flight information service shall, whenever
available, be provided in an operationally integrated form.
Operational flight information service broadcasts, when provided, should consist of
messages containing integrated information regarding selected operational and
meteorological elements appropriate to the various phases of flight. These broadcasts
should be of three major types, i.e. HF, VHF and ATIS.

WhenATISisprovided:
 theinformationcommunicatedshallrelatetoasingleaerodrome
 the information communicated shall be updated immediately when a
significant change occurs
 the preparation and dissemination of the ATIS message shall be the
responsibilityoftheairtrafficservices
 individual ATIS messages shall be identified by a designator in the form of a
letter ofthe ICAO spelling alphabet. Designators assigned to consecutive ATIS
messages shall be in alphabetical order
 aircraft shall acknowledge receipt of the information upon establishing
communication with the ATS unit
 the appropriate ATS unit shall, in the case of arriving aircraft, provide the
aircraft with the current altimeter setting when needed

4
  the meteorological information shall be extracted from the local meteorological
report.

Alertingservice
Alerting service will accomplish the objectives of notifying appropriate organizations
regarding aircraft in need of search and rescue aid
Alertingserviceshallbeprovided:
 forallaircraftprovidedwithairtrafficcontrolservice
 insofaraspracticable,toallotheraircrafthavingfiledaflightplanor otherwise known
to the air traffic services
 toanyaircraftknownorbelievedtobethesubjectofunlawful interference

Uncertaintyphasewhen
 no communication has been received from an aircraft within a period of thirty
minutes after the time a communication should have been received, or fromthe
time an unsuccessful attempt to establish communication with such aircraft was
first made, whichever is the earlier
 an aircraft fails to arrive within thirty minutes of the estimated time of arrival
last notified to or estimated by air traffic services units, whichever is the later
Exceptwhennodoubtexistsastothesafetyoftheaircraftand itsoccupants

ScopeandProvisionof ATCs

The need for the provision of air traffic services shall be determined by consideration
of the following:
a) thetypesofairtrafficinvolved;
b) thedensityofairtraffic;
c) themeteorologicalconditions;
d) Suchotherfactorsasmayberelevant.
All air traffic services units shall be supplied with up-to-date information on existing
and forecast meteorological conditions as necessary for the performance of their
respective functions.
Unitsprovidingareacontrolserviceshallbesuppliedwith:

5
  SIGMET and AIRMET information, special air-reports, current meteorological
reports and forecasts, particular emphasis being given to the occurrence or
expected occurrence of weather deterioration
 Current pressure data for setting altimeters, for locations specified by the flight
information center or area control center concerned
 Unitsprovidingapproachcontrolserviceshallbesuppliedwith:
 Current meteorological reports and forecasts for the airspace and the
aerodromes with which they are concerned.
 Current pressure data for setting altimeters, for locations specified by the
unitproviding approach control service.
 Currentsurfacewind
 Runwayvisualrangemeasurement(RVR)

Unitsprovidingtowercontrolserviceshallbesuppliedwith:
 Current meteorological reports and forecasts for the airspace and the
aerodromes with which they are concerned.
 Currentpressuredataforsettingaltimeters,forlocationconcerned
 Currentsurfacewind
 Runwayvisualrangemeasurement(RVR)
 Operationally significant conditions of the movement area, including the
existence of temporary hazards, and the operational status of any associated
facilities at the aerodrome
 A controlled flight shall be under the control of only one air traffic control
unit at any given time.
Areacontrolserviceshallbeprovided:
a) byanareacontrolcentre;or
b) by the unit providing approach control service in a control zone or in a control
area of limited extent which is designated primarily for the provision of
approach control service, when no area control centre is established.
Approachcontrolserviceshallbeprovided:
a) byanaerodrome controltower or anarea controlcentre, when it is necessaryor
desirable to combine under the responsibility of one unit the functions of the
approach control service and those of the aerodrome control service or the area
control service; or
6
 b) by an approach control office, when it is necessary or desirable to establish a
separate unit.
Aerodromecontrolserviceshallbeprovidedbyanaerodromecontroltower.
Flight information service and alerting service shallbe provided as follows:
a) Within a flight information region: by a flight information centre, unless the
responsibility for providing such services is assigned to an air traffic controlunit
having adequate facilities for the exercise of such responsibilities;
b) Within controlled airspace and at controlled aerodromes: by the relevant air
traffic control units

4. Visualflightrules (VFR)areasetofregulationsunderwhicha pilotoperates anaircraft

inweatherconditions generally clearenoughtoallow thepilotto seewhere the aircraft is
going. Specifically, the weather must be better than basic VFR weather minima,i.e.
invisual meteorological conditions (VMC), as specified in the rules ofthe relevant
aviation authority. The pilot must be able to operate the aircraft with visual reference
to the ground, and by visually avoiding obstructions and otheraircraft.
If the weather is below VMC, pilots are required to use instrument flight rules, and
operation of the aircraft will primarily be through referencing the instruments rather
than visual reference. In a control zone, a VFR flight may obtain a clearance from air
traffic control to operate as Special VFR.
Visual meteorological conditions (or VMC) that is, conditions in
whichpilotshave sufficient visibility to fly theaircraftmaintaining visual
separationfromterrainandotheraircraft
Instrumentmeteorologicalconditions (IMC)isanaviationflightcategorythat
describesweatherconditionsthatrequirepilotstoflyprimarilybyreferenceto
instruments,andthereforeunderInstrumentFlightRules(IFR),
TheboundarycriteriabetweenIMCandVMCareknownastheVMCminima
and are defined by:visibility, cloud ceilings (fortakeoffsand landings), and cloud
clearances.

VFR requires a pilot to be able to see outside the cockpit, to control the aircraft's
altitude,navigate,andavoidobstaclesandotheraircraft. [2]Governingagencies

7
establish specific requirements for VFR flight, including minimum visibility, and
distance from clouds, to ensure that aircraft operating under VFR are visible from
enough distance to ensure safety.
Undervisual meteorological conditions the minimum visual range, distance from
clouds, or cloud clearance requirements to be maintained above ground vary by
jurisdiction, and may also vary according to the airspace in which the aircraft is
operating.
The VFR pilot is required to "see and avoid"obstacles and other aircraft. Pilots flying
under VFR assume responsibility for their separation from all other aircraft and are
generally not assigned routes or altitudes by air traffic control (ATC). Depending on
the category ofairspace in which the flight is being conducted, VFR aircraft may be
required to havea transponderto help Air TrafficControlidentifytheaircraftonradar in
order that ATC can provide separation to IFR aircraft.
Meteorologicalconditions that meet the minimum requirements for VFR flight are
termed visual meteorological conditions (VMC). If they are not met, the conditionsare
considered instrument meteorological conditions (IMC), and a flight may only operate
under IFR. IFR operations have specific training requirements andcertification
required of the pilot, and increased equipment requirements for the aircraft.
Additionally, an IFR flight plan must usually be filed in advance. For efficiency of
operations, some ATC operations will routinely provide "pop-up" IFR clearances for
aircraft operating VFR, but that are arriving at an airport that does not meet VMC
requirements. For example, in the United States, California's Oakland (KOAK),
Monterey (KMRY) and Santa Ana (KSNA) airports routinely grant temporary IFR
clearance when a low coastal overcast forces instrument approaches, while the rest of
the state is still under visual flight rules.
Inmostif not all countriesof theworld,VFRpilotsalsohavean optionfor
requestingSpecial VFR when meteorological conditions at an airport are below normal
VMC minima, but above Special VFR requirements. Special VFR is only intended to
enable takeoffs and landings from airports that are near to VMC conditions, and may
in some States only be performed during daytime hours if a pilot does not possess an
instrument rating.
VFR flight is not allowed in airspace known as class A, regardless of the
meteorologicalconditionsexceptafterfailureoftwowayradiocommunications.In
8
the United States, class A airspace begins at 18,000 feet msl, and extends to analtitude
of 60,000 feet msl.

AllaircraftwhenoperatedasVFR flightsshallbeequippedwith:
1. AirSpeedIndicator(allaircraftwithspeedlimitationsexpressedintermsof Mach
number shall be equipped with a Mach Number Indicator).
2. PressureAltimeter
3. MagneticCompass
4. RPMindicatorforeachengine
5. Outside air temperature indicator on aircraft on engine having provision for
carburetor heat control in case carburetor Air Temperature Gauge is not
installed.
6. Oilpressureindicatorforeachengine
7. Oil quantity indicator for each tank (instead of an instrument, it may be a dip
stick).
8. CHTindicator foreachaircooledenginehavingratedBHPabove250.
9. Temperature gauge for determining the temperature of the coolant for each
liquid cooled engine.
10. Oiltemperaturegauge foreachaircooledenginehavingrated BHPabove250.
11. Manifold pressure gauge for each engine, fitted with variable pitch propeller
and/or is super charged.
12. FuelGaugeindicatingthequantityoffuelineachtank.
13. Landing gear position indicator for the aircraft fitted with retractable landing
gear.
14. Anaccuratetimepiece,indicatingtimeinhours, minutesandseconds.,and
15. suchotheritems/equipmentas maybeprescribedbythe manufacturer/DGCA for
particular installation
5. Instrument flight rules (IFR) is one of two sets of regulations governing all
aspects of civil aviation aircraft operations; the other is visual flight rules (VFR).
"Rules and regulations established by the FAA to govern flight under conditions in
which flight byoutside visual reference is not safe. IFR flight depends upon flying by
reference to instruments in the flight deck, and navigation is accomplished by
reference to electronic signals.[1]It is also a term used by pilots and controllers to
indicate the type of flight plananaircraft is flying, suchas anIFR or VFR flight plan.
9
Instrument flight rules permit an aircraft to operate in instrument
meteorologicalconditions (IMC) in contrast to VFR. They are also an integral part of
flying in classAairspace. "Class A" airspace exists over and near the 48 contiguous
U.S. states and Alaska from 18,000 feet above mean sea level to flight level 600
(approximately 60,000 feet inaltitude depending on variables suchas atmospheric
pressure). Flight in "class A" airspace requires pilots and aircraft to be instrument
equipped and rated and tobe operating under Instrument FlightRules(IFR). Mostjet
aircraft operate in "class A" airspace for the cruise portion of their flight and are
therefore required to utilize IFR procedures. Procedures and training are significantly
more complex as a pilot must demonstrate competency in conducting an entire cross-
country flight in IMC conditions, while controlling the aircraft solely by reference to
instruments.
Instrument pilots must meticulously evaluate weather, create a very detailed flightplan
based around specific instrument departure, en route, and arrival procedures, and
dispatch the flight.
InstrumentforIFR
All aircraft when operated in accordance with the instrument flight rules or when the
aircraft cannot be maintained in a desired attitude without reference to one or more
flight instruments, shall be equipped with:
1. amagneticcompass;
2. anaccuratetimepieceindicatingthetimeinhours,minutesand seconds;
3. asensitivepressurealtimeter;
4. airspeedindicator,
5. aturnandslipindicator
6. anattitudeindicator(artificialhorizon);
7. aheadingindicator(directionalgyroscope);
8. means of indicating whether the supply of power to the gyroscopic instruments
is adequate;
9. a meansofindicatinginthe flight crewcompartment theoutside air
temperature;
10. arate-of-climbanddescentindicator;and
11. Suchadditionalinstrumentsorequipmentasmaybeprescribedbytheappropriate
authority.
10
6. Classificationofairspaces
ATS airspaces in India are classified and designated in accordance with following.
The two categories of airspace are: regulatory andnonregulatory. Within these
twocategoriestherearefourtypes:controlled,uncontrolled,specialuse,andother airspace.
Controlled airspace is a generic term that covers the different classifications of
airspace and defined dimensions within which air traffic control (ATC) service is
provided in accordance with the airspace classification. Controlled airspace consists
of:
 ClassA
 ClassB
 ClassC
 ClassD
 ClassE

ClassA:
IFR flights only are permitted; all flights are provided with air traffic control
serviceand are separated from each other.
ClassB:
IFRandVFRflightsarepermitted;allflightsareprovidedwithairtrafficcontrol service and
are separated from each other.
ClassC:

11
IFR and VFR flights are permitted, all flights are provided with air traffic control
service and IFR flights are separated from other IFR flights and from VFR flights.
VFR flights are separated from IFR flights and receive traffic information in respectof
other VFR flights.
ClassD:
IFR and VFR flights are permitted and all flights are provided with air traffic control
service,
IFR flights are separated from other IFR flights and receive traffic information in
respect of VFR flights. VFR flights receive traffic information in respect of all other
flights. Airspaces in terminal areas, control areas, control zones and aerodrome traffic
zones have been classified and designated as class D airspace.
ClassE:
IFR and VFR flights are permitted; IFR flights are provided with air traffic control
service and are separated from other IFR flights. IFR flights receive trafficinformation
in respect of VFR flights; VFR flights receive traffic information in respect of all
other flights, as far as is practical. Class E is not be used for control zones. Airspaces
in designated ATS routes outside terminal areas, control areas and control zones,
where air traffic control service is provided, have been classified and designated as
class E airspace.
ClassF:
IFR and VFR flights are permitted. All IFR flights receive an air traffic advisory
service and all flights receive flight information service, if requested. Airspaces in
designated ATS route segments outside terminal areas, control areas and control
zones, where air traffic advisory service is provided, have been classified and
designated as class F airspace.

UncontrolledAirspace
Class G
Uncontrolled airspace or Class G airspace is the portion of the airspace that has not
been designated as Class A, B, C, D, or E. It is therefore designated uncontrolled
airspace. Class G airspace extends from the surface to the base of the overlying Class
E airspace. Although ATC has no authority or responsibility to control air traffic,
pilots should remember there are visual flight rules (VFR) minimums which apply to
Class G airspace.

12
IFR and VFR flights are permitted and receive flight informationservice if requested.
Airspaces other than those in Class D, E and F have been classified and designated as
class G airspace.

SpecialUseAirspace

Special use airspace or specialarea of operation (SAO) is the designation for airspace
in which certain activities must be confined, or where limitations may be imposed on
aircraft operations that are not part of those activities. Certain special use airspace
areas can create limitations on the mixed use of airspace. The special use airspace
depicted on instrument charts includes the area name or number, effective altitude,
time and weather conditions of operation, the controlling agency, and the chart panel
location. On National Aeronautical Charting Group (NACG) en route charts, this
informationis availableononeoftheendpanels. Specialuseairspaceusuallyconsists of:

 Prohibitedareas
 Restrictedareas
 Warningareas
 Militaryoperationareas(MOAs)
 Alertareas
 Controlledfiringareas(CFAs)

13
14
7. VarieskindsofSeparations

Inair traffic control, separation is the name for the concept of keepinganaircraft outside a
minimum distance from another aircraft to reduce the risk of those aircraft colliding, as
well as prevent accidents due to wake turbulence.

Air traffic controllers applyrules, knownas separation minima to do this. Pairs of aircraft
to which these rules have been successfully applied are said to be separated: the risk of
these aircraft colliding is therefore remote. If separation is lost between two aircraft, they
are said to be in a conflict.

When an aircraft passes behind or follows another aircraft, wake turbulence minima are
applied due to the effect of the wingtip vortices of the preceding aircraft on the following
aircraft. These minima vary depending on the relative size of the two aircraft. This is
particularly acute on final approach with a smaller aircraft following larger aircraft.

Basedonfollowingcategories

 Regulatory-ClassA,B,C,D,andEairspace
 Nonregulatory-militaryoperationarea(MOA),warningareas,alertareas,and controlled
firing area
 Thecomplexityordensityofaircraft movements
 Thenatureoftheoperationsconductedwithintheairspace
 Thelevelofsafetyrequiredand
 Thenationalandpublicinterest

Whichaircraftneedseparating?

It is a common misconception that air traffic controllers keep all aircraft separated.
Whether aircraft actually need separating depends upon the class of airspace in which the
aircraft are flying, and the flight rules under which the pilot is operating the aircraft. As
stated bythe U.S. FAA, The pilot has the ultimate responsibility for ensuring appropriate
separations and positioning of the aircraft in the terminal area to avoid the wake
turbulence created by a preceding aircraft.

Therearethreesetsofflightrulesunderwhichanaircraftcanbe flown:

 VisualFlightRules(VFR)
 SpecialVisualFlightRules(SVFR)
15
  InstrumentFlightRules(IFR)
PublictransportflightsarealmostexclusivelyoperatedunderIFR,asthissetofrules allows flight
in regions of low visibility (e.g. cloud). On the other hand a large amount of private flying
in lightaircraft isdone under VFRsince this requiresa lower levelofflying skill on thepartof
thepilot,andmeteorological conditionsin which apilotcansee and
avoidotheraircraft.Asitsnamesuggests,SVFRisaspecialinfrequently-usedsetof rules. For the
purposes of separation, controllers consider SVFR to be the same as IFR.
Airspaceexistsinsevenclasses,AtoG,indecreasingorderofairtrafficcontrol
regulation.ClassesAtoEarecontrolledairspaceandclassesF andGareuncontrolled airspace. At
oneendofthescale inclasses Aand Bairspace, allaircraft must beseparated from each other.
At the other end of the scale in class G airspacethere is no requirement for any aircraft to
be separated from each other. In the intermediate classes some aircraft areseparatedfrom
eachotherdependingon theflightrulesunderwhichtheaircraftare
operating.ForexampleinclassDairspace,IFRaircraftareseparatedfromotherIFR aircraft, but
not from VFR aircraft, nor are VFR aircraft separated from each other.

8. ALTIMETERSETTINGPROCEDURES
For flights in the vicinity of aerodromes and within terminal control areas the vertical
position of aircraft shall be expressed in terms of altitudes at or below the transition
altitudeand intermsof flight levelsatorabove thetransitionlevel. While passingthrough the
transition layer, vertical position shall be expressed in terms of flight levels when climbing
and in terms of altitudes when descending.

Forflightsenroutetheverticalpositionofaircraftshallbeexpressedintermsof:
 flightlevelsatorabovethelowestusableflight level;
 Altitudesbelowthelowestusableflight level.
Determinationofthetransitionlevel
The appropriate ATS unit shall establish the transition level to be used in the vicinity of
the aerodrome(s) concerned.
The transition level shall be the lowest flight level available for use above the transition
altitude established for the aerodrome(s) concerned. Where a common transition altitude
has been established for two or more aerodromes which are so closely located as torequire
coordinated procedures, the appropriate ATS units shall establish a common transition
level to be used at any given time in the vicinity of the aerodrome.

16
MinimumcruisinglevelforIFRflights
Cruisinglevelsbelowtheestablishedminimumflightaltitudesshallnotbeassigned.
Provisionofaltimetersettinginformation
The flight crew shall be provided with the transition level in due time prior to reaching it
during descent.
This may be accomplished by voice communications, ATIS broadcast or data link.
Thetransitionlevelshallbe included inapproachclearancesorrequestedbythepilot.
AQNHaltimetersettingshallbe included inthedescentclearancewhenfirstclearedtoan altitude
below the transition level, inapproachclearances or clearances to enter the traffic circuit,
and in taxi clearances for departing aircraft, except when it is known that the aircraft has
already received the information.
Determinationofthetransitionlevel
The appropriate ATS unit shall establish the transition level to be used in the vicinity of
the aerodrome(s) concerned

9. Establishmentanddesignationoftheunitsprovidingairtrafficservices
The air traffic services shall be provided by units established and designated as follows:
Flight information centers shall be established to provide flight information service and
alerting service within flight information regions, unless the responsibility of providing
such services within a flight information region is assigned to an air traffic control unit
having adequate facilities for the discharge of such responsibility.
Air traffic control units shall be established to provide air traffic control service, flight
information service and alerting service within control areas, control zones and at
controlled aerodromes.
Identificationofairtrafficservicesunits andairspaces
An area control centre or flight information centre shall be identified by the name of a
nearby town or city or geographic feature. An aerodrome control tower or approach
control unit shall be identified by the name of the aerodrome at which it is located. A
control zone, control area or flight information region shall
Divisionofresponsibilityofcontrol
DivisionofResponsibilityforControlbetweenAirTrafficControlUnits
Between a units providing aerodrome control service and a unit providing approach
control service. Except for flights which are provided aerodrome control service only, the
controlofarrivinganddepartingcontrolledflightsshallbedividedbetweenunits

17
 providing aerodrome control service and units providing approach control service as
follows:
Arriving aircraft: The responsibility for the control of an aircraft approaching to landshall
be transferred from the unit providing approach control service to the unit providing
aerodrome control service when the aircraft:
a) Isinthevicinityoftheaerodrome,and
i) it is considered that approach and landing will be completed in visual reference to
the ground,or
ii) ithasreacheduninterruptedvisualmeteorologicalconditions,or
b) haslanded,whicheveristheearlier.
Departing aircraft: The responsibility for control of a departing aircraft shall be
transferred from the unit providing aerodrome control service to the unit providing
approach control service:
a) whenvisualmeteorologicalconditionsprevailinthevicinityoftheaerodrome.
i) priortothetimetheaircraftleavesthevicinityoftheaerodrome,or
ii) priorto the aircraft entering instrument meteorologicalconditions, whichever is the
earlier;
b) wheninstrumentmeteorologicalconditionsprevailattheaerodrome.
i) immediatelybeforetheaircraftenterstherunwayin-usefortake-off,or
ii) immediately after the aircraft is airborne, if local procedures render such action
preferable.
Between a unit providing approach control service and a unit providing area control
service
When area control service and approach control service are not provided by the same air
traffic control unit, responsibility for controlled flights shall rest with the unit providing
area control service except that a unit providing approach control service shall be
responsible for the control of:
a) arrivingaircraftthathavebeenreleasedtoitbytheareacontrolcentre;
b) departingaircraftuntilsuchaircraftarereleasedtotheareacontrolcentre.
Under approach sequence conditions the unit providing area control service shall normally
be responsible for clearing aircraft to the holding point, and for including holding
instructions and expected approach time in such clearances. A unit providing approach
controlserviceshallassumecontrolofarrivingaircraft,providedsuchaircrafthavebeen

18
released to it, upon arrival of the aircraft at the point agreed for transfer of control, and
shall maintain control during approach to the aerodrome.
The control of more than one approach sequence may be effected by a unit providing
approach control service, provided the division of control between the unit providing area
control service and the unit providing approach control service is defined in instructions
approved by the appropriate ATS authority and is basically consistent with the foregoing
procedures.

19